Centrifugal type safety and arming spring for a fuze



Dec. 4, 1962 H. G. WENIG 3,066,606

CENTRIFUGAL. TYPE SAFETY AND ARMING SPRING FOR A FUZE Filed 001;. 4, 1960 2 Sheets-Sheet l E 3 7 2+1 2 Eg' :QL

NVENTOR. Harm '[cf BAA/anig Dec. 4, 1962 H. G. WENIG 3,065,606

CENTRIFUGAL TYPE SAFETY AND ARMING SPRING FOR A FUZE Filed Oct. 4, 1960 2 Sheets-Sheet 2 INVENTOR. Har' 1:11:1 G .Wanig 3,60,605 Patented Dec. 4, 1%52 7 i hee the Army Filed Oct. 4, 1960, Ser. No. 60,533 3 Ciaims. (Cl. 102-75) This invention relates to a centrifugal type safety and arming device for a fuze, and more particularly to a mechanism acting as a torque drive, a governor and a safety and arming device for a point detonating fuze.

In the present invention, a spring having a weight mounted at its center is attached at one of its ends to the fuze body and at its other end to a rotor which acts under centrifugal force to rotate a rotor element through an arc of 90 with respect to the longitudinal fuze axis and align an explosion train to arm the fuze. The fuze is adapted to function after a delay of 800 microseconds and is achieved by a steel ball which is released upon impact force to be dislodged from a retaining position adjacent the axis of rotation of the fuze and move outwardly through an involute groove and impinge upon a primer element located at the end of the groove. The time required for the ball to travel the length of the groove furnishes the required impact delay, thus acting both as an impact delay and a firing element At high rotational speeds, such as projectile spin, the weight will, under centrifugal force, tend to move radially outward, bending the spring which causes the rotor to rotate to its position in the fuze whereby the fuze becomes armed, its rotation being limited to 90 by a stop pin riding in a groove. At rotational speeds less than the required arming speed, the spring will prevent the rotor from moving 90, whereby the fuze cannot become armed. The time required for the rotor movement is a function of the centrifugal force and the mass moment of inertia of the rotor. The spring and weight device and the rotor are designed to give the specified arming delay and the torque is controlled by the size of the weight which must be such that under centrifugal force, it will exert a torque greater than the friction torque by an amount which results in the correct arming time for the rotor.

It is therefore a prime object of this invention to provide a safety and arming device for a point detonating fuze functioning only at a sufficient centrifugal force.

It is another object to provide a spring and weight device acting upon centrifugal force to rotate a rotor 90 from a safety position to arm a fuze.

Another object is to provide a centrifugally responsive spring means to release a shaft carrying a ball whereby the shaft will be moved rearwardly upon impact force to release the ball to fire a detonator.

A further object is to provide a spring having a weight affixed to its center to act upon centrifugal force to apply sufficient torque upon a rotor for rotating it 90 to arm a fuze, the torque exacted being greater than the friction torque by an amount which results in the correct arming time for the rotor.

A still further object is to provide a delay arming mechanism for a fuze wherein the mechanism acts as a torque drive, a governor and a safety and arming spring.

Other objects and advantages of the invention will be apparent during the course of the following description.

In the accompanying drawings, forming a part of this specification, and in which like numerals are employed to designate like parts throughout the same,

FIG. 1 is a longitudinal section through a fuze illustrating a safety and arming device constructed in accord- 2?. ance with the present invention, and the operating elements being shown in an unarmed position;

FIG. 2 is a section taken along lines 22 of FIG. 1,

FIG. 3 is a section taken along lines '33 of FIG. 1,

FIG. 4 is a section taken along lines 4-4 of FIG. 1,

FIG. 5 is a section taken along lines 5-S of FIG. 1,

FIG. 6 is a section taken along lines 6-6 of FIG. 1,

FIG. 7 is a section taken along lines 77 of FIG. 1,

FIG. 8 is a section taken along lines 8-8 of FIG. 1,

FIG. 9 is a section taken along lines 9-9 of FIG. 7,

FIG. 10 is a perspective view of the rotor shaft,

FIG. 11 is a section taken along lines Il ll of FIG. 8, and

FIG. 12 is a perspective view of the spring and weight device.

Reference character 1 indicates a cup shaped fuze body having a threaded outer wall portion 2 for attaching fuze body 1 to a projectile 3 which carries the usual booster charge 4 contained in a booster cup 5 which may be fastened by any suitable manner to fuze body 1. Fuze body 1 is provided with an annular shoulder 6- disposed forwardly of the threaded portion 2 and abuts the forward face of projectile 3.

Fuze body 1 extends forwardly of shoulder 6 as at 7. A stator element indicated generally by 8 is received in the forward portion of the fuze body 1 and the extension 7 is crimped about its forward edge as at 9 for securing the stator within the body 1.

The rear wall 10 of fuze body 1 is substantially thicker than the side wall and is provided with an integral forwardly extending cylindrical boss 11. Boss 11 is bored axially as at 12 and is further provided with a transverse forward slot 13, open at its forward end and is best viewed in FIG. 6, for a purpose to be described later.

Stator 8 is cylindrical in shape and is provided with an axially disposed square bore 14-. The rearward face of stator 8 is counterbored as at 15 and a portion of the wall formed by the counterbore is cut away as at 15 as best viewed in FIG. 4.

A rearwardly extending arcuate wall 16 is provided on the floor of counterbore-IS and is provided with a concave edge 17 as best seen in FIGS. 1 and 3 for a purpose to be later apparent.

A cylindrical rotor, indicated generally by 18 is provided and consists of two sections, i.e., a rear section 19 and a front section 20. Sections 19 and 20 are held together for rotational movement by pins 21. (See FIG. 9.)

The forward section 20 of rotor 18 is provided with a square axial bore 22. An involute groove 23 is provided in the rearward face of section 20 and extends from bore 22 to a passage 42. A primer element 25 is disposed in the outward end of involute groove 23 and a flash detonator 25 is located in the passage 24. A stop pin 26 is fixed in the forward face of rear wall 10 (see FIGS. 6 and 7), and is adapted to ride in a arcuate groove 57 (see FIG. 7) in the peripheral surface of the rearward section of rotor 18.

Rearward section 19 is provided with an axially and forwardly disposed square bore 27 and a round rearwardly disposed bore 20.

Both sections of rotor 15 are mounted on a shaft element indicated generally by 29 (see FIG. 10). This shaft defines an enlarged square portion 30 adapted to slide in square bores 22 and 27, and a reduced rectangular rearward portion 31 adapted to be received in slot 13. Shaft 30 is further provided with a rearward stub shaft 32 and a coaxial forward stub shaft 33. Rearward shaft 32 is adapted to be slidably received in cylindrical recess 12 while forward shaft 33 is adapted to be slidably received in a cylindrical recess 34 in a square plunger rod indicated generally by 35. Plunger rod 35 slidable in a bore 36 defines a conical head portion 37 receivable in a conical socket 38 located axially in the rearward face of a plunger, indicated generally by 39. Plunger 39 defines a member having a conical base portion '40 and a forwardly extending integral stern portion 41. The rearward face 42 is planar and the plunger 39 is held in spaced relation for the stator 8 when in assembled relation by a spacer ring 43. A nose cap 44 is fitted about the plunger 39, spacer ring 43 and stator 8 and is crimped on the forward extension 7 of the fuze body 1 as at 45.

Delay means for the fuze is provided and consists of a steel ball 46 normally received in a concave socket 47 in shaft 29 and which is retained in socket 47 by concave edge 17 on wall 16 of the stator 8 and a beveled arcuate edge in the forward face of rotor 18.

An arming device indicated generally by 49 (see FIG. 12) is provided to normally hold rotor 18 in a safe position and consists of a spring 50 bent along its middle as at 51 to receive a weight 52. Spring St) is further bent at its respective ends in opposite directions as at 53 and 54. End of spring 50 is secured in a bore 55 in stator g and end 54 is secured in a bore 56 in rotor 18. The middle portion 51 and weight 52 are normally disposed in counterbore of stator 8.

An explosion train from primer to the booster charge 4 is provided and consists of a flash detonator 58 in the rearward section 19 and a lead cap 59 in the wall 1% of fuze body 1.

Operation As illustrated in FIG. 1, the parts are in their unarmed position, with the arming device 49 holding the rotor 18 against rotation. In this position, ball 46 is restrained from movement as the reduced rectangular portion 31 of shaft 29 is out of alignment with the transverse slot 13, hence the shaft 29 cannot be moved rearward.

When the projectile is fired from a gun (not shown) linear setback will force the rotor 18 rearwardly against the fuze body wall 10 and frictional force prevents any possible rotation of rotor 18. After the projectile leaves the gun, et-back force will diminish and permit the arming device to function. Arming device 49 functions upon centrifugal force, due to projectile spin, to cause the weight 52. on spring 59 to move in a radial direction and rotate the rotor 13. Movement of rotor 18 is limited through an arc of 90 by virtue of stop pin 26 riding in arcuate groove 57 in the peripheral surface of the rearward section 19, thus providing a suitable delay. Upon reaching the limit of rotation, the fuze will be armed as the reduced rectangular portion 31 of shaft 29 is then aligned with transverse slot 13 in the cylindrical boss 11 on wall 1% of fuze body 1, and flash detonator 58 will align with fiash detonator 25 in recess 24 and lead cup 59 in wall it) to complete the explosive train.

Upon target impact, the nose cap 44 will deform and plunger 41 will be forced rearwardly to crush spacer ring 43 and drive plunger rod and shaft 29 rearwardly until the reduced rectangular portion 31 is completely received in transverse slot 13 in wall 10, thus releasing ball 46 from its secured position. Ball 46 will then be freed to travel outwardly through the involute groove 23 and impinge on primer 25 whereupon booster charge 4 will be exploded.

The base portion of plunger 41 may be provided with a series of bores 6% for air relief and to provide weight reduction of 39. Stator 8 may also be provided with a relief port 61.

Cutaway portion 15 in wall 16 formed in counterbore 15 provides sufficient space to allow weight 52 to move It will be apparent from the foregoing description, that a novel centrifugal force responsive delay device has been designed by the spring and weight 29 and ball 46. The fuze mechanism provides both a delay mechanism l that is reliable and possessing a high degree of safety. The mechanism further is capable of withstanding considerable abuse such as mishandling, etc., and can only become armed during a high rate of projectile spin.

it is to be understood that the form of our invention, herewith shown and described, is to be taken as a preferred example of the same, and that various changes in the shape, size and arrangement of parts may be resorted to, without departing from the spirit of the invention, or the scope of the subjoined claims.

I claim:

1. In a centrifugal type safety and arming device for a fuze, a fuze body having a threaded outer wall for engagement with a projectile, and a thickened rear wall, said rear wall defining a forwardly extending cylindrical boss, there being an axial bore therein and a traversely disposed slot forwardly of said axial bore, a stator fixed in the forward portion of said fuze body, said stator having a square axial bore therein and a rearward counter bore, there being a rearwardly extending arcuate segment integral to said stator and spaced from said square bore, said segment having a concave outer face, a rotor rotatably mounted in said fuze body disposed rearwardly from said stator, said rotor comprising a forward section and a rearward section, said forward section having a square axial bore, there being an involute groove in the rearward face of said forward section extending from said square bore, a detonating element in the terminal end of said groove, a powder train in said rotor and said body, said rearward section of said rotor having an axial square bore in its forward portion and a round counterbore in its rearward portion, a square shaft slidable in said square bore in said rotor and rotatable therewith, said shaft defining a reduced rectangular portion adapted to be received in said transverse slot in said boss, and a rearward stub shaft receivable in said bore in said boss, there being a forward stub shaft on said square shaft in axial alignment with said rearward stub shaft, a square plunger rod slidable in said square bore in said stator, said plunger rod having an axial rearward bore adapted to receive said forward stub shaft on said square shaft, and a conical head portion at its forward end, an impact actuated plunger disposed forwardly of and in axial alignment with said square plunger rod, said impact actuated plunger having a rearwardly disposed conical recess adapted to receive said conical head portion on said square plunger rod, arming means for said fuze disposed between said rotor and said stator comprising a wire spring connected at one end to said rotor and at its other end to said stator, a weight fixed medially upon said spring, said weight adapted to move outwardly upon centrifugal force to rotate said shaft and said rotor to align said detonator with said powder train in said body, means limiting rotational movement of said rotor upon reaching said alignment comprising a stop pin fixed in the forward face of said rear wall of said fuze body, said stop pin adapted to ride in an arcuate groove in the rearward surface of said rotor, an impact delay means for said fuze comprising a socket in said square shaft, a ball in said socket, said ball normally retained in said socket by said concave face on said wall of said segment on said stator, said ball being released from said socket upon impact on said plunger rod whereby plunger rod and said square plunger moves rearwardly to release said ball to move into said involute groove and strike said detonating element.

in a centrifugal type safety and arming mechanism for a projectile fuze, a fuze body for attachment to a projectile, said body defining a thickened rearward wall and a centrally disposed, forwardly extending boss, said wall having a central bore and said boss having a coaxial, forwardly disposed transverse slot, a stator fixed in the forward portion of said body, a rotor axially disposed between said wall and said stator, a shaft slidable in said rotor, said shaft defining an enlarged square portion, a

rearwardly extending reduced rectangular portion receivable in said transverse slot, a rearward stub shaft receivable in said bore in said wall, and a forward stub shaft in axial alignment with said rearward stub shaft, a plunger rod slidably mounted in said stator forwardly of said shaft and in axial alignment therewith, said plunger rod defining a square cross section and a forwardly disposed integral conical head, there being a rearwardly disposed axial bore in the rearward end of said plunger rod, said last named bore adapted to receive said forward stub shaft on said shaft, an impact actuated plunger mounted in axial alignment with and forwardly of said plunger rod, said impact actuated plunger having a rearward axial conical recess adapted to receive said conical head portion on said plunger rod, said impact actuated plunger normally being spaced forwardly from said stator and axially of said plunger rod, detonating means carried by said rotor, impact delay means normally held in place in said shaft and held against release by said rotor, and arming delay means disposed between said rotor and said stator, said rotor adapted to rotate to an arming position upon centrifugal force and said shaft is rotated to align said reduced rectangular portion with said slot in said boss on said wall of said body whereby, upon impact on said impact actuated plunger, said impact actuated plunger will slide said plunger rod and said shaft rearwardly whereby said reduced rectangular portion is received in said slot and said impact delay means is released to detonate said detonator element in said rotor.

3. A centrifugal type safety and arming device for a projectile fuze comprising in combination, a body for attachment to a projectile and having a rearward wall, a

stator fixed at the forward end of said body, a rotor mounted for rotation between a safety and an armed position in said body and disposed in axial alignment between said rearward wall and said stator, a detonator carried in said rotor; impact responsive detonating means for said fuze comprising a driven plunger axially slidable in said stator, a driving plunger mounted axially and forward of said driven plunger and a shaft slidably mounted in said rotor rearwardly of said driven plunger and adapted to rotate with said rotor; an impact delay detonating means normally retained by said shaft and said rotor; and a centrifugal force responsive time delay means between said rotor and said stator, said time delay means comprising a wire spring bent at its medial portion and a weight fixed to said bent medial portion, said wire spring being bent at its ends thereof for attachment to said rotor and said stator, said weight adapted to swing outwardly upon projectile spin to rotate said rotor from said safety to said armed position, and said impact responsive means adapted to act upon impact on said driving plunger to slide said driven plunger against said shaft whereby said shaft will slide rearwardly and release said detonating means to detonate said detonator in said rotor.

References Cited in the file of this patent UNITED STATES PATENTS 2,663,260 Thompson Dec. 22, 1953 2,837,999 Lindsay June 10, 1958 2,953,991 Leonard Sept. 27, 1960 

